How much Google knows about you? The google dashboard. I found out the google search I did last Saturday on “enable root on Mac” (by going to google => “My Account” => “web history”). I believe there is a setting a google user can change to disable google to collect the data. But for me sometimes it could be useful because I want to repeat an old search I did a while back. A related question for business is:
How do you know about visitors to your website?
My title may be a bit misleading, I think a better question is how do you measure the performance of your web site? In other words, which page is highly viewed, which page gets no attention etc. Here comes web analytics (Wiki). Web analytics came of age lately as Omniture being bought by Adobe recently.